1. Field of the Invention
The present invention relates to a device for a flexible magnetic disk. More particularly, it relates such a device which clamps a flexible disk in association with a spindle connected to a motor by means of a cup member.
2. Description of the Prior Art
FIG. 5 shows a conventional device for a flexible magnetic disk. A spindle 3 is directly connected to a motor 2 and a flexible disk 1 is pressed to the spindle 3 by a cup member 4 whereby the flexible disk 1 is rotated. The cup member 4 is exactly pressed to the spindle 3 by an auxiliary cup member 5 such that cooperating annular surfaces of the spindle 3 and the cup member 4 can clamp the disk 1 with a cylindical portion of the cup member 4 fitted in the central aperture of the disk. The cup members 4, 5 are brought to a correct positions by a coil spring 6 and are connected to a shaft pin 7. The shaft pin 7 is supported by a bridge base 8 by means of E-type rings 9.
In the device for the flexible magnetic disk having the above-mentioned construction, a flexible disk 1 having both surfaces of polyester film coated with magnetic powder is mounted on the spindle 3. When a door attached to the device is closed, the cup members 4, 5 fitted to the bridge base 8 which is connected to the door descend in the arrow mark direction A to be pressed to the spindle 3; thus the flexible disk 1 is clamped at a correct position.
In the conventional device, when the flexible disk 1 clamped by the cup member 4 and the spindle 3 is rotated, there takes place the phenomenon of an eccentric rotation or an undulating rotation of the flexible disk due to permissible error of the inner diameter of the central aperture, thereby damaging accuracy in writing-in and reading-out of information.